A373975 - OEIS

%I #7 Jun 24 2024 17:10:13

%S 1,0,0,0,0,0,0,1,0,0,0,1,0,0,0,0,0,1,0,1,0,0,0,0,0,0,1,1,0,1,0,0,0,0,

%T 0,0,0,0,0,0,0,1,0,1,1,0,0,0,0,1,0,1,0,0,0,0,0,0,0,0,0,0,1,1,0,1,0,1,

%U 0,1,0,0,0,0,1,1,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,1,0,1,1,0,0,1,0,0,1,0,0,0,0,1,0,0,0,1,0,1,1,0,0,0,0,0,0,1,1

%N a(n) = 1 if the number of prime factors with multiplicity is a multiple of 3, otherwise 0.

%H Antti Karttunen, <a href="/A373975/b373975.txt">Table of n, a(n) for n = 1..100000</a>

%H <a href="/index/Ch#char_fns">Index entries for characteristic functions</a>

%H <a href="/index/Eu#epf">Index entries for sequences computed from exponents in factorization of n</a>

%F a(n) = [A001222(n) == 0 (mod 3)], where [ ] is the Iverson bracket.

%F a(n) >= A101605(n).

%o (PARI) A373975(n) = !(bigomega(n)%3);

%Y Characteristic function of A145784.

%Y Cf. A001222.

%Y Cf. also A065043, A101605, A358753, A373588, A373596, A373836 for similar characteristic functions.

%K nonn

%O 1

%A _Antti Karttunen_, Jun 24 2024